The present disclosure herein relates to methods of forming photo detectors and, more particularly, to methods of forming photo detectors using a selective epitaxial growth (SEG) process.
Recently, various technologies for photo devices have been remarkably developed. In particular, technologies for optical communication devices and image sensors have been continuously developed. The optical communication devices may utilize lights as information media, and the image sensors may receive lights reflected from objects to generate electrical signals. The image sensors or photo detectors may be fabricated using semiconductor materials. The image sensors or the photo detectors may include an absorption layer formed of the semiconductor material and the absorption layer may receive lights to generate electron-hole pairs. The electrons and the holes generated in the absorption layer may move toward two separate electrodes, thereby generating the electrical signals.
In general, PIN photo detectors of an indium gallium arsenide (InGaAs) exhibiting a high reactivity and a high speed may be widely used as high performance photo detectors which can be integrated with complementary metal oxide semiconductor (CMOS) circuit devices. However, the PIN photo detectors of an InGaAs may have a disadvantage of high fabrication costs.
To solve the above disadvantage, various fabrication techniques have been developed to form high performance photo detectors exhibiting high reliability and excellent electrical characteristics.